Core barrel



Oct. 8,l 1940. F. F. HILL CORE BAR-REL Filed July 6, 1956 INVENTQR. Frank F.' H1!! BY 5f/ff ATTORNEY.

Patented Oct. 8, 1940 UNITED STATES PATENT A OFFICE CORE BARREL Application July 6, 1936, Serial No. 88,930

6 Claims.

The present invention relates to an improved core barrel for use with core drills employed in deep well drilling, and is a continuation in part of my copending application Serial No. 749,454, filed Oct. 22, 1934. More particularly the invention pertains to improvements in an apparatus or structure for taking representative samples of the formation being drilled Without the necessity of removing the drilling equipmentfrom the well l bore each time such core-taking operation is performed.

In the parent application it is stated that in usual drilling operations it is desirable to obtain samples of the formation being drilled wherever i and-whenever there is reason to believe that a producing stratum has been encountered. In fact it is quite common to obtain a complete log of the formation encountered during the drilling of a well bore. Previously it has been customary to provide the lower portion of the drill pipe, and the bit attached or suspended therefrom, with a coreor sample-taking .and retaining device usually termed core barrel, a core or sample of the formation entering said core barrel and rising up- Wardly therein as the drilling advances. When the sample is to be brought to the surface for purposes of inspection, the use of such a core barrel necessitates the withdrawal of the whole string of drill pipe with the core barrel to the :0 surface. In deep wells this is a long and laborious operation necessitating the removal of the drill pipe section by section until all of it has been withdrawn from the bore. If a continuous log of the formation is desired, and since the usual i5 length of a core barrel does not exceed 20 feet,

the use of the above mentioned core barrel necessitates the repeated withdrawing and lowering of the whole string of pipe after drilling has progressed the length of the core barrel. Obviously,

lo this type of operation is very cumbersome, involving considerable loss of time and expenditure of money. n

To obviate these disadvantages, the parent application disclosed and claimed a method and ap- 45 paratus or structure for taking representative samples of the formation being drilled without the necessity of removing the drill pipe and bit from the well bore each time the core-taking operation is performed. Briefly stated, the 50- method consists in using a core-taking device which may be lowered into a drill pipe by freely' introducing said device into the drill pipe, allowing the weight of the device and that of the packing means on said device (in connection with the 55. mud fluid circulated down through the drill pipe) (Cl. Z55-72) to lower said device into core-taking position at the lower end of the drill pipe, obtaining a core by the usual drilling operation while maintaining the core-taking device in said core-taking position at the lower end of the drill pipe, and re- 5 versing the direction of circulation of mud fluid to force the core-taking device together with the core therein upwardly through the drill pipe to thereby recover said core barrel without the necessity of withdrawing the drilling equipment from the well bore.

The core-taking structure disclosed and claimed in said co-pending application consists of a barrel provided at-its lower end with a core-cuttingbit and with longitudinal grooves on the outer face thereof adapted to cooperate with splines on the inner walls of the circular opening through the bit and to permit the rotation of the core barrel together with the bit. It has been found, however, that the provision of a core-cutting bit at theklower end of the core barrel as well as the rotation of the core barrel together with the drill pipe and bit, do not permit the recovery of a full sized core, i. e. a core equal to the distance drilled through.

It is therefore one of the objects of the present invention to provide an improved core-taking device adapted to recover and hold a complete and representative core of the formation being drilled.

It is a further object of the present invention to provide an improved core-taking instrument adapted to be freely lowered into position in the lower portion of the drill pipe and recoverable without the withdrawal of the drill pipe in which the core-taking structure is maintained stationary and in non-rotating position during the drilling and core-taking operations.

The above and other objects may be attained by providing the lower end of the drill pipe with a bit adapted to cut a core, and by providing a eorereceiving structure adapted to be freely lowered through the drill pipe and into position in the lower portion of said pipe and within the drill bit to receive the core thus formed, the core-receiving structure resting on a smooth or roller-bear- V ing type of thrust bearing which permits the sliding of vthe core-receiving barrel over the core without rotation, while the drill pipe and bit are rotated to cause the formation of the core. As in the case of the structure disclosed in the parent application, the core-receiving structure-is provided with packing means which cause the instrument to act as a piston, the mud pressure moving the core-taking instrument downward through the drill pipe into core-receiving position, or up- 55.

wardly to the surface, depending on the direction of flow of mud uid through the drill pipe. Because of the provision of these packing means which close the annular space between the corereceiving instrument and the inner walls of the drill pipe, the core-receiving barrel located below said packing means is provided with a swivel joint, thereby permitting the upper portion of the instrument to rotate with the drill pipe and, at the same time, holding the core barrel itself stationary with respect to such rotation.

Briefly stated, the structure described and claimed herein provides lfor a string of drill pipe preferably having a substantially uniform internal diameter throughout its length, a drill bit at the lower end of said drill pipe adapted to cut a core, means within said bit adapted to receive and support a core-taking instrument, and a coretaking instrument adapted to be freely introduced into the drill pipe and moved downwardly and upwardly therein by the action of the mud fluid circulated through said'pipe, said core-taking instrument comprising a core barrel, packing means at the upper end of said barrel to close the annular space between the drill pipe and the barrel, and a swivel connection between the packing meansI and said barrel to permit the maintenance of the barrel stationary while th packing means abutting against the inner walls of the drill pipe are rotated therewith.

The invention further resides in the provision of a thrust bearing in the core bit', said bearing acting as the support for the core-receiving instrument and aiding in the holding of the corebarrel of said core-receiving instrument stationary with respect to rotation during the drilling and core-taking operations.

The invention also resides in the particular construction and arrangement of the corebarrel, and in its combination with the drill pipe and drill bit. A fuller understanding thereof may be obtained from the drawing which discloses said embodiments of the invention by way of illustration and in which:

Figure 1 is a diagrammatic longitudinal sectional view of a bore hole showing a drill pipe suspended therein from a kelly passing through a rotary table, said drill pipe carrying a bit at its lower end and containing the core-receiving instrument in position in the lower portion of the drill pipe;

Figure 2 is a sectional view of the upper portion of the core-receiving instrument disposed within the drill pipe;

Figure 3 is a sectional view of the lower portion of the core-receiving instrument in position in the lower portion of the drill pipe;

Figure 4 is a view in elevation of the uppermost end of the core-receiving instrument or structure taken at right angles to the view thereoi' shown in Figure 2;

Figure 5 is a bottom view of a preferred embodiment of a core-cutting bit;

Figure 6 is a detailed elevation of the guiding means adapted to guide and align the core-receiving instrumentwith the bore through the l core-cutting bit;

Figure 7 is a sectional view of a modiiied embodiment of a bali check seat employed in connection with one of the passages within the corereceiving instrument; and v Figure 8 is an elevational view of said ball check seat.

As shown in the drawing and more particularly in Figures 2 and 3 thereof, the core-receiving instrument or structure consists of a cylinder or core barrel I0, the lower end of which is provided with the usual core-retaining means l2. 'I'he upper end of cylinder is closed by a head I3 carrying at its upper end a cage |4 and communicating therewith by means of openings |5. Cage |4 contains a ball check valve |1. Ports |8 communicate the interior of cage |4 with the space surrounding the instrument structure. The upper end 20 of the cage-containing portion of the structure is provided with an upwardly projecting rod 2| terminating in a boss or nut 22. Said boss 22 rests on the upper end cfa pipe 24 the length thereof. A swivel joint or bearing 25 -is disposed between section 20 and the lower end of said pipe 24. Such an arrangement permits the relative rotation of pipe 24 with respect to the rest of the structure suspended therefrom.

'I'he upper end of pipe 24 is attached, as by means of threads 28 to a nipple 29, said nipple having in its lower portion a bore 30 adapted to receive boss 22. The upper portion of nipple 28 is also provided with a' central longitudinal bore 32 which communicates, at substantially its lower end, by means of ports 33 with the space surrounding nipple 29. I'he bore carries a ball check valve 35, the function of which will be described hereinbelow. The upper end of bore 32 is equippedv with a seat 31 adapted to receive ball 35 when it is in its upper position.

The upper end of nipple 29 is attached to a swedged pipe 40 having a central bore 4| therethrough. On its circumference pipe 40 carries two expansible and contractable packing elements generally indicated by the numeral 42. Each of these packing means consists of a flexible cupshaped element 43 the base of which is rigidly attached to pipe 40 by means of a ring 44. 'I'he flexible elements 43 are normally held in contracted position, i. e. away from the inner walls of the drill pipe by means of spring members 45. A1- though the drawing shows the cup-shaped elements 43 as facing each other, they may be also disposed in the opposite direction so that the cupshaped members face away from each other. Pipe 40 is attached at its upper end to a nipple 41 similarly provided with a longitudinal bore 48 and with'a circular shoulder 49 on its circumference, the purpose of this shoulder being described hereinbelow. The upper end of nipple 41 is attached to element 5| provided with bore 52 and a lifting member or link 53.

For the purpose of receiving and recovering a sample of the formation being drilled, the abovedescribed core-receiving instrument is freely dropped into the interior of a string of drill pipe. As stated previously, it is preferable to have the string of drill pipe with a uniform interior diameter to prevent the core-taking structure from catching on and hanging up on any projection within the drill pipe. Such a string of pipe is shown diagrammatically in Figure 1. As shown in said figure, the well bore is lined with some sort of casing 51 provided at its upper end with a head 58 and a branch line 58 equipped with a valve 58, the purpose of which will be described hereinbelow in .connection with the description of the operation of the assembly. An ordinary type of swivel head n is mpnded in the usual manner from the top of the derrick. A hollow kelly 54 is attached to the lower end of swivel 53- and passes through a rotary table 55 being held therein by means of`spiders 56. 'I'he lower end of nelly 54 is threaded into a coupling 88 from which the string of drill pipe generally indicated by the numeral 10 is suspended.

The lowermlost section 13 of the drill pipe carries bit 14 adapted to bore the hole and simultaneously to cut the core or sample to be recovered. As shown in the drawing and more particularly in Figures 3 and 5, the body of bit 14 is provided with cutters 15 adapted to drill the well bore. The bit is also provided with a centrally disposed longitudinal bore 11 extending axially through said bit, said bore being of a dlameter substantially equal to or slightly smaller than the internal diameter of the core-receiving barrel lll described above. The lower or outer edge surrounding bore 11 is equipped with corecutting teeth 18. Within the body of bit 14, bore 11 is enlarged to provide a seat for a thrust bearl ing. As shown more particularly in Figure 3, said thrust bearing consists of two rings 80 and 8| disposed one on top of the other and being provided with roller bearings 82 thereinbetween. A core instrument receiving and aligning means, shown more specifically in Figure 6, is disposed on ring 8|. This means comprises a ring 83 provided with upwardly extending and outwardly flared fingers 84. The bit 14 is also provided with fluid passages 85 and 86 which are employed for the circulation of mud fluid when the central bore 11 through said bit is closed by means of the core-receiving instrument.

In operation, the drilling is carried out by the rotation of rotaie7 table B5, said rotation being communicated to kelly 84 held by spiders 86 and then transmitted through drill pipe 10 to bit 14. The circulation of mud fluid is obtained by introducing the same through a flexible hose 81, the fluid passing through swivel 63, kelly 64 and drill pipe 10 until lt reaches bit 14. The mud fluid then washes teeth 15 and 18 of said drill bit 14 and rises in the annular space between drill pipe 18 and casing 51 to be withdrawn from the system through line 59.

When the operations have been carried down to a point where it is desired to take a sample of the formation being drilled, the rotation of the rotary table 85 is temporarily stopped. Kelly 64 is then disconnected from coupling 89 and the core-receiving instrument described hereinabove is freely dropped into the drill pipe 10. Thereafter kelly 68 is again attached to coupling 69 and the circulation of mud fluid is resumed. The force of the mud fluid moving downwardly within drill pipe 18 will cause the expansion of the core-receiving instruments lower packing element 42 which acts as a piston to force said corereceiving instrument downwardly. When the core-receiving instrument reaches the bottom of the drill pipe the lower end of cylinder or core barrel ||l of said instrument is guided by fingers 84 of the aligning means shown in Figure 6 to cause said core barrel to pass within ring 83 and onto the upper surface of the upper ring 8| of the thrust bearing disposed in bit 14.

When the core-receiving instrument is thus in position in the lower portion of the drill pipe and on the thrust bearing in bit 14, the recovery of the respective sample of the formation may be carried out by simultaneously rotating and lowering the drill pipe. During this core-taking drilling, the mud iluid is continuously circulated by introducing it through flexible hose 81, dow'n through the drill pipe, up through the annular space between the drill pipeand the casing 51, and out through line 59. The mud pressure thusY maintained in the drill pipe 10 keeps the packing element 42 in open position to act as a piston for the core-receiving instrument, said instrument being thus held downwardly against the thrust bearing and therefore in core-receivingr position.' During such core-taking drilling operation, the mud fluid passing downwardly through drill pipe 10 enters bore 52 in element.

5| of the core-receiving instrument, then passes through bore 48 in nipple 41, and bore 4| in pipe 40. The mud fluid then enters bore 32 in nipple 29 and passes through ports 33 into the annular space between the core-receiving instrument and the walls of drill pipe 10 below the packing element 42. Due to thevelocity and pressure of the circulated mud fluid, ball 35 is held in the lower portion of bore 32 and away from seat 36, thus permitting the passage of the fluid through the core-receiving instrument. The mud fluid then passes downwardly around cylinder or core barrel I0, and through ports 85 and 88 in bit 14 to wash teeth 15 and 18 thereof and to pick up the cuttings caused by the drilling operations. The mud uid then rises through the annular space between drill pipe 10 and casing 51 and is withdrawn from the system through line 59.

. As is obvious, the rotation of drill pipe 10 and of bit 14 will cause teeth 15 to cut a hole in the formation. At the same time teeth 18 will form a core of such formation, said core entering through opening 11 in said bit. The gradual drilling and lowering of the drilling structure as described above will therefore cause this core to enter the core-receiving barrel I0. The mud iluid trapped in the core barrel by said core will pass through openings l5 in head I3. After raising ball |1 in cage I4, the mud will then flow through ports |8 into the space around the core-receiving instrument.

Since the core or sample cut` by the core-producing teeth 18 has substantially the same diameter as the inside diameter of core barrel HJ, the core will fit rather vtightly in said barrel.

the core barrel l0 by means of rod 2| and boss 22 from that portion of the core-receiving instrument carrying the packing means, as well as the provision of the swivel joint 26, however, holds the core barrel I8 stationary with resect to rotation. Also, the use of thrust or ball bearing 80, 8| eliminates any friction between the rotating drill bit 14 and the lowermost edge of core barrel l0. It is obvious that the above described means permit the rotation and lowering of the drill pipe and drill bit and the simultaneous lowering of core barrel I0 overthe core drilled by teeth 18 without any rotation of said core barrel and without the resultant breakage and loss of the core thus formed.

When the' desired length of ncore has been taken and when it is desired to recover the corereceiving instrument `and the core contained therein without the necessity of withdrawing the annular space between casing 51 and drill pipe 10. The fluid then flows into the drill pipe through ports or openings inl'drill bit 14 and rises in the annular space between the drill pipe and the core receiving instrument. 'I'he :duid pressure then collapses the lower packing element 42 and expands the upper one. The uid also enters through ports 33 into the bore 32 in nipple 29. The upward movement of the fluid in said bore 32 lifts ball check valve 35 and causes it to abut against seat 31 to close the opening 3 6 therein. It is thus obvious that the fluid cannot pass around or through the core receiving instrument. Therefore the continued introduction` of mud fluid through line 59 will now cause the upper exible element 43 to act as a piston and to raise the instrument substantially to the top of drill pipe 10. "I'he mud iiuid above the core-receiving 'instrument is withdrawn from the system through flexible pipe 81 attached to swivel 63.

'Ihe upper end of drill pipe 10 is equipped with means for retaining the core-receiving instrument during the operation of uncoupling the kelly and of removing the instrument from the interior of the drill pipe. For this purpose, as shown in Figure 1, a'nipple 88 is placed between the uppermostdrill pipe joint 10 and coupling 69, and is provided with spring fingers or latches 89. The lower ends of thesengers are rigidly attached to the interior of nipple 88 while their upper ends are adapted to protrude inwardly into the interior of the bore in said nipple.

When the circulation of the mud, fluid raises the core-receiving instrument into the nipple, fingers 88 slide over the uppermost element 5| of the instrument and catch the same under the shoulders 49, thus preventing the instrument from falling back into the drill pipe during the operation of uncoupling-the kelly. The corereceiving instrument may then be removed-by its lifting member 53.

It is thus obvious that by means of the abovedescribed method and structure representative samples of the formation may be repeatedly obtained without the necessity of withdrawing the drill pipe. The core-takingoperation is carried out by uncoupling kelly 64 and nipple 88 from .the drill pipe 18, freely dropping the core-receiving instrument into the drill pipe, obtaining a core by continued drilling, and raising the core-receiving instrument with the core to the surface by reversing the direction of mud circulation.

It is to be noted that the core-retaining means I2 in the lower portion of core barrel I0 breaks off the core and retains it inthe barrel during the upward flight of the core-receiving instrument.

As stated hereinabove, the core-receiving instrument is provided with a longitudinal bore which communicates the space above said instrument with the annular space below the packing elements 42. This bore permits circulation of iiuid during the core-taking operation. However, when it is desired to raise the core-receiving instrument to the surface, it is necessary to close this bore so that the mud fluid being circulated up through the drill pipe will not be bypassed through the instrument but will act as exerted force on the packing element to cause upward flight of the instrument. The ball check valve 35 is provided for this purpose. During downward flow of the mud fluid through the drill pipe, ball check valve 35 is held by the force of the mud in the lower part of cage or bore 32, thereby permitting the above-described mud circulation. However, when circulation is reversed, it is necessary to raise said balll so that it will abutl against seat 31 and close or stop by-passing ofthe mud fluid through the core-receiving instrument. It has been found that this ball check valve may be of hollow metallic construction or of a material possessing a specific gravity lighter than the mud being circulated. The ball may be advantageously made of rubber. Such construction will tend to keep the valve on seat 31, thus closing the passage or bore through the core-receiving instrument except when the mud fluid is pumped downwardly through the drill pipe, at which time the pressure ofthe uid will unseat the ball and permit the circulation of the uid through the bore in the portion of the instrument carrying the packing means or element.

It'has been discovered, however, that when the ball 35 is made of a resilient material such as rubber, or when it is of a hollow construction, the mud fluid, being circulated under a comparatively high pressure, compresses the ball and may force it into and through seat 31. For

this purpose, I have developed the seat shown in Figures 7 and 8. Briefly stated, this seat consists of an annular ring 9| adapted to fit into the groove provided for it in the upper portion of passage 32, and of an arched body 92 closing the opening through said ring and having a plurality of perforations 93. It is obvious that such a structure will permit the circulation of the mud fluid through perforations 93, and will still re tain the ball 31 when it is forced against the arched body 82. It is clear that any other type of a valve which permits fluid passage in only one direction may be employed instead of the structure. shown in the drawing and described hereinabove.

The present invention is capable of many other modifications. Instead'of the ballbearing type of thrust bearing shown in Figure 3 and employcd to support the lower end of the corereceiving instrument and to permit the core barrel I0 to remain stationary with respect to rotation, it is possible to employ a steel or other metallic ring having a highly polished upper surface, said ring acting as the thrust bearing and similarly permitting the maintenance of core barrel I0 stationary with' respect to rotation. Furthermore, the core-receiving instrument may 1 be provided with one or more sleeves or piston rings which may'be employed instead of the packing means 42, said sleeves or rings being .adapted to`force the core-receiving instrument is preferably' employed in connection with a drill pipe string having a substantially uniform diameter throughout its length,it is obvious that the core-receiving instrument described and claimed herein may also be used or employed in the ordinary type of drill pipes having constrictions at or about the tool joints employed therewith. In such such case the packing means 42 may be constructed so that it will expand and contract to fit the bore of the drill pipe to which the corereceiving instrument is passing.

'I'he terms core-taking and core-receiving as used in the present specification refer to the same structure, and are used to denote an instrument adapted to receive and retain the core or sample cut by the core-cutting teeth on the bit.

Although the present invention has been shown and described in a simple and practical form, it is recognized that certain parts or elements thereof are representative of other parts, elements or mechanisms which may be used in substantially the same manner to accomplish substantially the same results. It is to be understood, therefore, that the invention is not to be limited to the details described herein but is to be accorded the full scope of the following claims.

I claim:

1. A core-receiving instrument adapted to receive and retain a core obtained during drilling with mud circulatiomwhich comprises a core-receiving and retaining barrel, packing-carrying means cooperating with said barrel, a swivel joint between said barrel and said means, a longitudinal bore through said packing-carrying means, a seat in said bore, and a ball adapted to close said bore by being brought against said seat, said ball being of such a specific gravity as to iioat in the circulated mud.

2. In a structure according to claim 1, wherein the ball adapted to close the bore through the packing-carrying means is of a hollow construction.

3. In a structure according to claim 1, wherein the seat comprises an annular ring having a curved perforated portion adapted to receive and hold the ball.

4. A core-receiving instrument which comprises a core-receiving and retaining barrel, packingcarrying means (zo-'operating with said barrel, oppositely opening cup-shaped packing means on said packing-carrying means, a swivel joint between said Abarrel and said packingcarrying means, a longitudinal bore through said packingcarrying means, and means Within said bore adapted to permit circulation only in one direction.

5. A drilling structure which comprises a string of pipe disposed in the well bore, a bit attached to the lower end of said string and provided with a central longitudinal bore therethrough, a thrust bearing disposed within said bit and around said bore, means co-operating with the upper portion of said pipe string and adapted to rotate said string and bit, means communicating with the upper portion of said pipe string adapted to cause mud fluid to circulate down through said string pipe and bit and up through the Well bore, and means co-operating with the upper end of the We11 bore and adapted to reverse the direction of mud circulation, in combination with a'core-receiving instrument adapted to ybe freely moved in either vertical direction in the well, said instrument comprising a core-receiving and retaining barrel, packing-carrying means co-operating with said barrel, a swivel joint between said barrel and said means, a longitudinal bore through said packing-carrying means, a seat in said bore, and a ball adapted to close said bore by being brought against said seat, said ball being of such specic gravity as to float in the mud fluid.

6. In a structure according to claim 5 wherein the packing on the packing-carrying means comprises a plurality of oppositely opening flexible cup-shaped elements.

FRANK F. HILL. 

